TX Winter Wx Threat # 10---cool/cold and wet?

[double D]

I just saw that TWC has some ice forecasted for the hill country. That is strange since there is no mention of it from the NWS. I think TWC must have seen something on the GFS and changed their forecast. I honestly do not see the hill country getting ice on Wednesday with highs in the 40's.

It seems like this week is going to turn out to be pretty chilly and the weekend might end up being warmer instead of cooler. Weather is so wacky.

[cctxhurricanewatcher]

Those are very compelling numbers AFM.

Considering you have researched the source region for this arctic airmass, I'm thinking your forecast of 12-15 below normal for a day or two looks pretty good at this point. And yes ... it is a far cry from anything historic or record-breaking.

Yeppers. I am on aboard with AFM now. January should be below normal when recorded in the record books at the end of the month. It looks like it may carry over to February even if we don't get any historic, pipe breaking stuff.

[Air Force Met]

Amazing that we can go from cold that rivals 1989 to a hardly impressive cold snap in just a few days time.

Not amazing to some of us who keep a mental tally of how often these forecasts of 83/89/1899 are posted here and elsewhere. I was warning in this very forum a week ago to not buy into the '83/'89 hype.


I'm still amazed at how some people - even some pro mets - practically scream "Icebergs in Galveston Bay" every time a block shows up. These are 50-yr and 100-yr events, they don't/won't happen very often.

And FWIW it seems just a handful are the culprits....but they say the same thing every winter and before long they have a flock of snow geese bowing before them. After several years of "buying" into the hype on a particular subscriber site, I had to learn the hard way and read the models myself.

Cold, wintery days in SETX is about 2 things:
1) A massive frigid dome of very high pressure in AK and NW Canada setup to do (what I call ) the Lee-side slide down the east side of the Rockies. You need an upper air high to kick the high out of it's source and that's about it. Gravity does the rest. SW flow aloft can be all over the place...it won't matter.

2) A cold airmass that comes down with some upper level support and some overrunning aloft that gets the wet-bulb process going. That will turn a high of 40 into a high of 30...

IF you don't have those two things...you can get a decent high to slide south under good upper level support...it will drop you into the 20's...maybe even the teens (edit: for lows / given how cold the airmass is originally)...but it won't have any staying power.

This particular airmass isn't abnormally cold. The pattern is abnormal...the airmass (in it's source region) isn't. So...by the time it moves out of its source region and modifies...your looking at temps 15-20 below normal in the coldest areas. NOthing to write home about.

[PTrackerLA]

I figured we'd see a few light freezes from this upcoming "arctic outbreak" much like this morning, but nothing more than that. It's very very difficult to see teens around here, which is why we haven't seen in happen in almost 11 years now. These "rival '83, '89" arctic outbreaks that get built up so much on here EVERY year are simply just that, hype. I'll take below normal temps because it is winter after all .

[Below N.O.]

Amazing that we can go from cold that rivals 1989 to a hardly impressive cold snap in just a few days time.

Not amazing to some of us who keep a mental tally of how often these forecasts of 83/89/1899 are posted here and elsewhere. I was warning in this very forum a week ago to not buy into the '83/'89 hype.


I'm still amazed at how some people - even some pro mets - practically scream "Icebergs in Galveston Bay" every time a block shows up. These are 50-yr and 100-yr events, they don't/won't happen very often.

And FWIW it seems just a handful are the culprits....but they say the same thing every winter and before long they have a flock of snow geese bowing before them. After several years of "buying" into the hype on a particular subscriber site, I had to learn the hard way and read the models myself.

Cold, wintery days in SETX is about 2 things:
1) A massive frigid dome of very high pressure in AK and NW Canada setup to do (what I call ) the Lee-side slide down the east side of the Rockies. You need an upper air high to kick the high out of it's source and that's about it. Gravity does the rest. SW flow aloft can be all over the place...it won't matter.

2) A cold airmass that comes down with some upper level support and some overrunning aloft that gets the wet-bulb process going. That will turn a high of 40 into a high of 30...

IF you don't have those two things...you can get a decent high to slide south under good upper level support...it will drop you into the 20's...maybe even the teens (edit: for lows / given how cold the airmass is originally)...but it won't have any staying power.

This particular airmass isn't abnormally cold. The pattern is abnormal...the airmass (in it's source region) isn't. So...by the time it moves out of its source region and modifies...your looking at temps 15-20 below normal in the coldest areas. NOthing to write home about.

Since, there will be a "Cross Polar Flow" can you tell what the current temperatures are over the North Pole?

[Air Force Met]

Since, there will be a "Cross Polar Flow" can you tell what the current temperatures are over the North Pole?

Temps are -20's near the pole....-30's south of the Pole and -43 NW of Greenland at Eureka (which is actually normal for them at this time of year). Prince Patrick Island is at -29 (norm:-33), NW of there is's -37. Pressures are 1020-1025 mb...so without any massive domes of high pressure...expect what cold air that does get dislodged (which is what the EURO is showing...and the other models) to move south into the midwest and northern plains and then spread SE and E under the upper level flow of the Polar Vortex.

BTW...records for those locations in Feb are on the order of -60 to -65....so they are no where near historic...and in some cases it is slightly above normal.

[aggiecutter]

According to the 12z EURO, and this has been its solution about 7 out the last 10 runs ,it drives the bulk of the cold air, whatever that may be, straight down the plains into Texas, not east. Click on the link below and you can see it for yourself. Myself, I'll trust the EURO over the operational GFS, which has proven over the years and this year with the last outbreak that it held up stationary at the Oklahoma-Kansas border that is absolutely clueless when dealing with Arctic air.

12z EURO:
http://www.ecmwf.int/products/forecasts ... uv850_z500

[Extremeweatherguy]

According to the 12z EURO, and this has been its solution about 7 out the last 10 runs ,it drives the bulk of the cold air, whatever that may be, straight down the plains into Texas, not east. Click on the link below and you can see it for yourself. Myself, I'll trust the EURO over the operational GFS, which has proven over the years and this year with the last outbreak that it held up stationary at the Oklahoma-Kansas border that is absolutely clueless when dealing with Arctic air.

12z EURO:
http://www.ecmwf.int/products/forecasts ... uv850_z500

At 0z Saturday it even has a 1038mb high sitting right over the TX/OK border...



That looks like a pretty cold setup to me!

Also, here is the full ECMWF loop for everyone else to look at: http://weather.cod.edu/forecast/loop.ecmwf850t.html <<It shows another reinforcing shot of cold by 0z Monday.

[rsdoug1981]

That's the 00z run from last night, EWG. The runs are similar, however.

[pwrdog]

Those are very compelling numbers AFM.

Considering you have researched the source region for this arctic airmass, I'm thinking your forecast of 12-15 below normal for a day or two looks pretty good at this point. And yes ... it is a far cry from anything historic or record-breaking.

It looks like Eureka; N. W. T. is the best Canada can do at -44 F.. That is just below normal but most of the arctic has been above normal for a while..

The last really cold weather was a few weeks back when parts of Siberia recoded lows of -78F to -80F... Most of that air spilled into central Asia where they had a pretty bad cold spell..

Here is a good link to the history of bad freezes in far south Texas for any of you interested in weather history .. They rank them subjectively relating to agriculture as...1899, 1989, 1888, 1873, 1983, 1852... But list many other bad freezes.. Interesting read....

http://www.raingardens.com/psst/articles/artic03.htm

[vbhoutex]

I greatly respect and appreciate the opiniions and the knowledge that all of the pro-mets and amatuers are putting forth in trying to "pin down" what is going to happen with this "otbreak. What I don't think I understand or may not have read enough of is-what is going to be the source region for this "outbreak"? Is it going to be a cross polar flow from Siberia or the polar vortex that is setting up over the N Great Lakes/S Canada? If the source region is Siberia are the temps their running at or belwo normal ? If the source region is Siberia will it feed into this already cold polar vortex and cool it further? I know some of this, if not all, has at least been talked about, but can anyone give me a concise answer?(If that is possible this far out)

[srainhoutx]

I greatly respect and appreciate the opiniions and the knowledge that all of the pro-mets and amatuers are putting forth in trying to "pin down" what is going to happen with this "otbreak. What I don't think I understand or may not have read enough of is-what is going to be the source region for this "outbreak"? Is it going to be a cross polar flow from Siberia or the polar vortex that is setting up over the N Great Lakes/S Canada? If the source region is Siberia are the temps their running at or belwo normal ? If the source region is Siberia will it feed into this already cold polar vortex and cool it further? I know some of this, if not all, has at least been talked about, but can anyone give me a concise answer?(If that is possible this far out)

Absolutely Great Question!

[cctxhurricanewatcher]

Well, surprisingly, NWS Austin/San Antonio is buying the Euro more than the GFS for the upcoming weekend. Usually they worship at the alter of the GFS.

GFS CONTINUES TO INSIST THAT THE ARCTIC AIRMASS TO OUR NORTH WON`T
MAKE IT TO SOUTH CENTRAL TEXAS BY THE WEEKEND. HAVE DECIDED TO
CONTINUE THE TREND OF ECMWF GUIDANCE AND PREVIOUS FORECAST PACKAGES,
WITH THE COLDER AIR ARRIVING ON SATURDAY. NEXT MONDAY MORNING`S
LOWS LOOK TO BE THE COLDEST OF THE FORECAST PERIOD, WITH THE HILL
COUNTRY DIPPING INTO THE MID 20S...AND TEMPERATURES AT OR A FEW
DEGREES BELOW FREEZING ELSEWHERE. HAVE LOWERED MAX TEMPS FOR THE
WEEKEND BY ABOUT 10-15 DEGREES AS COMPARED TO GFS, BUT GENERALLY
IN THE UPPER 40S TO MID 50S RANGE WITH PARTLY CLOUDY SKIES. KEEP
IN MIND THAT FORECAST CONFIDENCE FOR DAYS 5-7 IS NOT VERY HIGH,
GIVEN THE INCONSISTENCIES OF MODEL GUIDANCE[img][/img]

[Air Force Met]

According to the 12z EURO, and this has been its solution about 7 out the last 10 runs ,it drives the bulk of the cold air, whatever that may be, straight down the plains into Texas, not east. Click on the link below and you can see it for yourself. Myself, I'll trust the EURO over the operational GFS, which has proven over the years and this year with the last outbreak that it held up stationary at the Oklahoma-Kansas border that is absolutely clueless when dealing with Arctic air.

12z EURO:
http://www.ecmwf.int/products/forecasts ... uv850_z500

I don't think that is what the EURO is doing at all. It drives the high south and then east. In 96 hours a weak high is on OK...and then in 120 hours it gets pushed east into AL/MS because of the upper flow. It never digs south into Texas. The train of highs that follow do the same thing...east one moving a little more to the east. Looking at the 850mb temps...the bulk of the cold air never heads south...it always stays under the upper flow. Remember...cold air advection will occur on the east side of these highs because that is where the source region is...so wherever these highs are...the coldest air will be east of that.

[Below N.O.]

According to the 12z EURO, and this has been its solution about 7 out the last 10 runs ,it drives the bulk of the cold air, whatever that may be, straight down the plains into Texas, not east. Click on the link below and you can see it for yourself. Myself, I'll trust the EURO over the operational GFS, which has proven over the years and this year with the last outbreak that it held up stationary at the Oklahoma-Kansas border that is absolutely clueless when dealing with Arctic air.

12z EURO:
http://www.ecmwf.int/products/forecasts ... uv850_z500

At 0z Saturday it even has a 1038mb high sitting right over the TX/OK border...



That looks like a pretty cold setup to me!

Also, here is the full ECMWF loop for everyone else to look at: http://weather.cod.edu/forecast/loop.ecmwf850t.html <<It shows another reinforcing shot of cold by 0z Monday.

I think that's a 1028.

[Air Force Met]

That looks like a pretty cold setup to me!

Also, here is the full ECMWF loop for everyone else to look at: http://weather.cod.edu/forecast/loop.ecmwf850t.html <<It shows another reinforcing shot of cold by 0z Monday.

But what does it do with the high 04/00z (Saturday evening)?

It moves it into northern Alabama and puts Texas unders trong return flow.

So...how is that a cold setup? Please tell me

You can't take one part of the model (the part you like) and throw out the rest (the part you don't)...because it is all built together like a house (of cards maybe). If you want the big high in 96 hours (with 850 mb temps still above freezing) as a cold setup...you have to take what the model is saying about that same high 24 hours later...that it is sitting in northern Alabama and we are under SE return flow at the sfc.

Again...we will see a colder than normal night or two...probably late weekend/early next week....but even the EURO is showing all who want to see that the coldest air is movnig east.

Here are the current 850 temp forecasts at there coldest (for SETX)

IAH - SAT 12Z 03-FEB 3.9 - MON 12Z 05-FEB -1.6
CRP - SAT 12Z 03-FEB 8.0 - MON 12Z 05-FEB 3.0
AMA - SAT 12Z 03-FEB -9.4 - MON 12Z 05-FEB -2.4
DFW-SAT 12Z 03-FEB -3.0 - MON 12Z 05-FEB -3.7
TXK - SAT 12Z 03-FEB -4.5 - MON 12Z 05-FEB -6.2
OKC - SUN 12Z 04-FEB -8.4 - MON 12Z 05-FEB -5.7
MEM - SAT 12Z 03-FEB -9.2 - MON 12Z 05-FEB -8.9
JAN - SAT 12Z 03-FEB -0.8 - MON 12Z 05-FEB -4.0
BHM - SAT 12Z 03-FEB -3.5 - MON 12Z 05-FEB -4.8
LIT - SAT 12Z 03-FEB -8.1 - MON 12Z 05-FEB -8.6
TOP - SAT 12Z 03-FEB -15.9 - MON 12Z 05-FEB -11.1
STL - SAT 12Z 03-FEB -15.7 - MON 12Z 05-FEB -14.2

This is a sample...but you can see how places with similiar latitudes, but further east get colder with the second shot on Monday (Top vs Stl; OKC vs MEM; DFW vs BHM). This is because the flow really can't be overcome by the weak highs.

[Extremeweatherguy]

Houston NWS has significantly cut back on weekend temperatures in the last 24-hours...

Friday Night: Partly cloudy, with a low around 38.

Saturday: Partly cloudy, with a high near 52.

Saturday Night: Partly cloudy, with a low around 37.

Sunday: Partly cloudy, with a high near 54.

This time yesterday the forecast was nearly 10 degrees warmer (showing low to mid 60s for highs next weekend).

BTW, the Houston NWS is now using the word "arctic" in their latest AFD:

UPPER LEVEL FLOW BECOMING MORE NORTHWESTERLY
DURING WEEKEND AS UPPER RIDGE BUILDS OVER EASTERN PACIFIC/EXTREME
WESTERN CONUS. GFS AND ECMWF DIFFERS IN HANDLING LONG WAVE PATTERN
OVER NORTH AMERICA ESPECIALLY LATE IN THE WEEKEND THROUGH NEXT
WEEK. THE ECMWF PATTERN OPENS THE POSSIBILITY OF BRINGING COLD
ARCTIC AIR MASS SOMETIME NEXT WEEK.

[Air Force Met]

I think that's a 1028.

Good catch.

And that's why it is sitting in northern AL 24 hours later! Big bulky highs go south because of their mass. Whimpy little highs go with the steering flow...which is what every on of these guys and gals are going to do. They start off on the wrong trajectory...none of them are diving due south...they all have a little bit of an eastward component and that develops more and more over time.

[rsdoug1981]

AFM,

Is there a definite way to determine (exact or ballpark) surface temps from temps at 850mb?

[Extremeweatherguy]

So, AFM, do you at least still agree with your statement two days ago that Houston will see a night in the 20s out of this?

I do think it will get colder than the GFS numbers and I do think the Houston area will see a night in the 20's...maybe mid-upper 20's at IAH before it is all said and done (not by late week though...probably by early next week/late weekend...)

http://www.storm2k.org/phpbb2/viewtopic ... t=#1513119